Vascular system steerable guidewire with inflatable balloon

ABSTRACT

A dilatation steerable guidewire for use in the vascular system having an inflatable balloon at the distal end and a bi-directional fluid pressure actuated ball valve forward of the balloon position. The guidewire construction provides torque and direction for manipulating the guidewire through the anatomy while the valve regulates fluid emission from the tip of the guidewire for visualization or into the balloon for inflation and deflation and is originated by fluid pressure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention resides in the field of guidewires for the insertion ofcatheters and other devices for the diagnosis and treatment of vasculardisease.

Guidewires are small diameter devices which provide torsional, axial andradial rigidity and are utilized to insert catheters into the anatomyand to guide catheters into areas of vascular anatomy. Guidewires aregenerally constructed of materials such as stainless steel rod or tubestock and have a coiled metallic spring around their entirety or only atthe distal end. The guidewire body, be it tube or rod, imparts torqueand axial strength while the spring is soft to be atraumatic to thevascular tissue. Guidewires can vary in size of outer diameter from afew thousandths to 0.080 inches and are designated by diameter inthousandths of an inch. Steerable guidewires generally range in size ofouter diameter from 0.010 inches to 0.020 inches.

Catheters are larger than guidewires and may be single or multiple lumentubes of somewhat different construction and materials. They aredesignated by French size and vary from a few French to as large as 50French for bypass surgery. One French equals 0.013 inches. Standarddiagnostic catheters are generally made of a soft material such asplastic and are used for a variety of diagnostic and therapeuticapplications. Diagnostic catheters are sometimes wire braid reinforcedor of coaxial construction with the inner tube having more rigidity thanthe outer tube to provide some control to the catheter.

Steerable PTCA catheters vary from as small as 3 French to as large as 5French. The smallest steerable catheter would be approximately 0.041inches. Steerable catheters, unlike diagnostic catheters, do notgenerally have any reinforce-ment to provide torque characteristics. Assuch steerable catheters are guided into the vasculature and to the areaof interest in the vasculature over steerable guidewires which providetorque and rigidity.

2. Description of the Prior Art

Prior to therapeutic catheters for the treatment of vascular disease,guidewires were used to straighten and safely guide diagnostic cathetersinto parts of the vascular system where radiopaque dyes were injected toilluminate the vasculature under fluoroscopy for studying the anatomyprior to therapy. With the advent of balloon and laser catheters forunblocking obstructions in small diameter vessels, such as the coronaryarteries, came the development of highly steerable guidewires of smalldiameter for accessing these lesions. The necessity for highly steerableguidewire devices came as a result of the tortuous pathways encounteredin the coronary vasculature. These steerable guidewires additionallywere designed with very soft atraumatic tips to avoid injury to thevasculature. Typically for a balloon dilatation procedure, a smalldiameter steerable guidewire is placed within a small diameter multiplelumen balloon catheter and the two advanced into the vasculature througha larger diameter guide catheter which has been placed from a remotevascular entry point. The guide catheter is similar to diagnosticangiographic catheters and is placed over a large diameter guidewirewhich straightens the guide catheter for entry into a remote area of thevasculature and facilitates manipulation of the catheter. At this pointthe large diameter guidewire is removed and the preformed tip of theguide catheter enables the catheter which has some torque capability tobe positioned at the site of entry of the therapeutic catheter into theparticular area of the vasculature. The guide catheter, unlike adiagnostic catheter, is stiffer and designed with the added supportcapability to facilitate advancement of the steerable guidewire andballoon catheter assembly into the remote narrow vasculature. The guidecatheter for coronary dilatation procedures would be advanced to thecoronary ostium. From this point the dilatation catheter and steerableguidewire assembly, which have been advanced through the guide catheteras an assembly, would exit from the guide catheter into the coronaryvasculature. The steerable guidewire would be advanced severalcentimeters out the tip of the balloon catheter. Because of theatraumatic tip and torque characteristics the steerable guidewire wouldbe used to access the area of obstruction. The balloon catheter wouldthen be advanced over the steerable guidewire across the lesion. Theballoon on the catheter would then be inflated to accomplish thetherapy. However, the steerable guidewire therefore would merely supportthe balloon catheter in reaching and crossing the lesion. With manysteerable systems pressure could be measured from the tip of the ballooncatheter in conjunction with a pressure from the guide catheter toprovide a gradient. The amount of gradient pre and post dilatation couldbe used as a measure of success. With these steerable systems, thetherapeutic catheter could then be pulled back on the steerableguidewire out of the narrowing to study the results by dye injection.The steerable guidewire remains across the lesion in order to re-crossthe lesion if necessary for additional therapy or should there beclosure of the vessel in order to re-open the vessel. Alternatively, thetherapeutic catheter can remain across the lesion and the steerableguidewire removed to be exchanged for another steerable guidewire ofvarying characteristics should this be deemed necessary.

The use of these systems is well known and a variety of systemscomprising various steerable guidewires and various balloon catheters incombination has been developed. The variety of steerable guidewires andcatheters for facilitating the procedure is extensive.

For example, in the area of guidewires, U.S. Pat. Nos. 4,545,390, Leary,and 3,789,841, Antoshkiw, both show distal tips formed of helicallywound springs surrounding fixed tapered cores. U.S. Pat. No. 3,631,848,Muller, describes an axially movable distal tip extension tube ofrelatively short length.

A coil tip with tapered face edges which will curve toward the taperwhen pulled upon by an internal control wire is disclosed in U.S. Pat.Nos. 3,452,740, and 3,452,742, both to Muller. U.S. Pat. No. 4,650,467,Bonello shows a similar arrangement for inclining the tip by retractionof a control wire affixed thereto.

Additionally, U.S. Pat. No. 3,528,406, Jeckel et al. teaches the use ofa fixed core wire having a reduced diameter in the spring tip portion ofthe wire. U.S. Pat. No. 3,625,200, Muller, discloses a curvable tipcomprising solid cylindrical links engaging each other with ball andsocket joints each of which is manipulatable by a fine core wire.Finally, U.S. Pat. No. 4,573,470, Samson shows a curved tip which isrotated in its entirety by rotating a core wire at the control handle.

The aforementioned guidewire designs and improvements were limited toproviding additional control characteristics to steerable guidewires tofacilitate catheter placement.

In the area of balloon catheters for dilatation or compression ofplaque, U.S. Pat. 4,323,071 discloses such a catheter in which twoconcentric tubes are employed, the inner tube adapted to fit over aseparate steerable guidewire. The distal end of the outer tube is sealedto contain the fluid. Visualization of the anatomy by fluoroscopy may beaccomplished ahead of the catheter and guidewire by infusion of dyethrough the central tube around the steerable guidewire and out thedistal tip of the catheter.

An alternative system is described in U.S. Pat. No. 4,582,181, Samson etal. in which a balloon is similarly formed in a catheter outer tubehaving a separate guidewire extending therethrough and inflation fluidis delivered through a tube disposed side by side with the guidewire. Inthis system the guidewire is moveable within the catheter axially butthe distal end is larger than the catheter tube through which it passesand as such may not be removed for guidewire exchange or may not be leftin place while the catheter is removed for catheter exchange as istypical in standard steerable catheter and guidewire systems. Fluid maybe infused in this system around the guidewire and out the distal tip ofthe catheter for dye tracing. The smaller wire permits a lower profilecatheter system but obviates wire exchange.

Finally in U.S. Pat. No. 4,573,470, Samson et al. describes aLow-Profile Steerable Intraoperative Balloon Dilatation Catheter systemwherein the catheter and the guidewire are bonded together to form aliquid-tight seal at the distal end of the catheter. The guidewire andballoon are manipulated as a unit with the guidewire fixed relative tothe catheter to prohibit axial movement of the guidewire within theballoon catheter but enabling the guidewire to provide torque to theballoon catheter as an integral unit. In this system fluid is containedsolely within the catheter.

The progression of developments in the area of steerableguidewire/catheter systems has enabled the access of smaller moretortuous vessels through the reduction of the overall outside diameter(profile) of the catheter/guidewire systems. In doing so the ability toprovide distal dye injections, catheter exchanges and guidewireexchanges has been lost in some of these designs.

SUMMARY OF THE INVENTION

The present invention may be summarized as a vascular system dilatationsteerable guidewire/balloon having an inflatable balloon disposed aboutthe circumference of the distal end. The invention eliminates the usualcatheter and guidewire combination entirely and incorporates thecatheter features into the novel guidewire.

Fluid under appropriate pressure for inflating the balloon is introducedinto the proximal end of the guidewire around a moveable butnon-removeable core wire. Valves composed of valve seats formed from theguidewire walls distal to the balloon and a moveable ball valve memberriding on a moveable core within the guidewire directs fluid into andout of the balloon through passageways in the guidewire walls under theballoon. Alternatively, the fluid is allowed to escape through the tipof the guidewire spring into the vascular system to carry out dyetracings in order to view the anatomy while guiding the device.

Additionally, a core member provides a means for controlling the distalcoiled spring tip of the guidewire to dynamically change the guidewirecharacteristics in vivo. Thus, and as will be further seen from thedisclosure below, the structure of the invention provides a multiplicityof features which have heretofore not been available in a steerableguidewire configuration.

The current invention provides desirable guidance/torque characteristicsof steerable guidewires with the therapeutic capabilities of the ballooncatheter while retaining the reduced overall profile of the guidewiredevice. In this manner there is no loss of steerability or therapeuticfunction. The design allows for distal dye injections, catheterexchanges and guidewire exchanges. In addition the design allows forincreased control of the guidewiare dynamics through the ability to varythe stiffness of the guidewire tip in-vivo.

According to one embodiment of the present invention, the valve may bearranged to be sealed either by fluid pressure to provide forward motionof the ball valve member or backward motion by negative pressure throughfluid withdrawal from the proximal end of the guidewire tube. Fluidpressure within the guidewire will accomplish forward valve closure andballoon inflation while fluid extraction from within the guidewire willaccomplish closure of the rearwardly disposed seat by the ball valvemember and will enable deflation of the balloon.

The stiffness of the coiled spring tip attached to the distal end of theguidewire tube is set by the choice of shape, coatings, materials,method of winding and diameters of the wire used to wind the coiledspring tip. The size, number and stiffness of the malleable safetywire(s) within the coiled spring tip determine the tip formability andcontribute to the stiffness and torque of the coiled spring tip.Stiffness is also set by the shape and point of attachment of the innerdistal connector tube within the coiled spring tip. The connector tubeattaches the coiled spring tip to the body of the guidewire. Theconnector also provides the forward valve seat. Dynamic in-vivo controlof tip stiffness is accomplished by advancement and retraction of theinner moveable core member with the attached distal stiffening member.The ball valve member rides on the moveable core member proximal to thedistal stiffening member. The moveable core member forward motion, iscontrolled by advancing or retracting the proximal end of the moveablecore member which exits from the proximal end of the guidewire tube. Theinner moveable core member is of small diameter to allow fluid passagearound the moveable core member from the proximal to distal end of theguidewire and, as such, does not provide additional frictional torque tothe outer body of the guidewire, the guidwire thus functions as astandard steerable guidewire but with in-vivo variable tip stiffness.

To augment this capability, the balloon may be disposed in a recessedarea of the guidewire wall such that the overall profile of theguidewire remains uniform; however this is not a requirement of thedevice wherein the balloon may be mounted on the exterior of theguidewire without a recessed area. This embodiment allows a conventionalsteerable balloon catheter to be placed over the guidewire as in aconventional steerable dilatation prodedure or for the exchange of adilatation catheter or the exchange of the steerable guidewire/ballooninvention for a conventional steerable guidewire during a procedure,thereby utilizing the device as a standard steerable guidewire.

The features and advantages of the invention will be more clearlyunderstood from the description of the preferred embodiment and drawingwhich follow.

DESCRIPTION OF THE DRAWING

The Figure is a cross-sectional view of the preferred embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the Figure a cross-sectional illustration of the steerableguidewire/balloon comprising the preferred embodiment of the inventionis shown in which flexible tube 10 is composed of stainless steel (orother suitable guidewire material). Inner tube 12 may be coated with anouter lubricious surface 14 such as teflon. Within tube 10 is a moveablecore 16. Helically wound spring tip 18 is attached to the distal end oftube 10 by connector 20. Tip 18 may be tapered as shown and is composedof stainless steel wire or other suitable radio dense material, such asplatinum. Within spring tip 18 is safety wire 21 which is attached tothe spring tip 18 and to connector 20 to prevent spring tip 18 fromuncoiling. Stiffening member 22 is attached to, or an integral unit withcore 16 and slidably fits within spring tip 18.

Recess 23 may be formed in tube 10 by, for example, cylindricalconnector 24 and tube walls 26 and 28. Balloon 26 may be disposed inrecess 23 and attached to connector 24 by any suitable adhesive.Metallic bands 32 may additionally be applied to further secure theballoon and provide bright radio opaque markers. Ports 34 and 36 inconnector 24 communicate with space 38 formed between core 16 and wall12 and allow fluid within space 38 to enter into or exit from recess 23for balloon inflation and deflation.

Connector 24 has valve seat 40 formed on the end thereof forward of theposition of the balloon. An additional valve seat 42 on connector 20 ispositioned forward of seat 40.

Ball valve member 44 is slidably mounted on moveable core 16. When ballvalve member 44 is in the appropriate contact position on either seat 40or 42 it prevents fluid passage. Forward motion and seating of the ballvalve member 44 is accomplished by fluid infusion and consequently fluidpressure within space 38. Rearward motion and seating of the ball valvemember 44 is accomplished by fluid withdrawal and consequently negativefluid pressure within space 38.

As will now be seen the apparatus disclosed above functions in thepreviously described manner to direct fluid either into the balloon forinflation or if the valve seat is not engaged, as shown, past the valveand out the tip of tube 10 into spring tip 18 and out through the springtip.

Further the ball valve will move to the rearward seat 42 when fluid iswithdrawn from the proximal end of tube 10 to deflate the balloon.

It will also be seen that the steerable guidewire/balloon may operateindependently of the fluid transfer function as a guidewire of varyingtip stiffness by axial movement of the core member 16 and stiffeningmember 22 and consequently stiffening spring tip 18.

Additionally, when the balloon is optionally disposed in recess 23 as isshown, a catheter of larger diameter may be advanced over tube 10 inaccordance with standard guidewire procedures and techniques as ispracticed in the art. Likewise a suitable larger lumen balloon cathetermay be advance over tube 10 when there is no recessed area.

Having fully described the configuration and method of use of thesteerable guidewire/balloon comprising the invention, the scope of thepatent is hereby defined by the following claims.

What is claimed is:
 1. For use in the vascular system a steerableguidewire/balloon apparatus comprising in combination:a. a length offlexible tubing having proximal and distal ends and interior andexterior walls and providing torsional, axial and radial rigidity; b. aninflatable balloon disposed about the exterior circumference of saidtubing at said distal end, said tubing having a passageway between saidinterior and exterior walls for admitting fluid to said balloon; c. aflexible axially moveable core member disposed within and along thelength of said tubing; and d. valve means disposed within said tubingforward of said passageway comprising a valve seat attached to saidtubing and a ball valve member slidably mounted on said moveable corefor containing said fluid within said tubing and selectively directingsaid fluid into said passageway and said balloon by sealing said valvemeans by fluid pressure.
 2. The apparatus of claim 1 wherein said valveseat is positioned to be sealed by said ball valve member by moving saidmember toward said distal end of said tubing by fluid pressure.
 3. Theapparatus of claim 1 wherein said valve seat is positioned to be sealedby said ball valve member by moving said member toward the proximal endof said tubing by fluid extraction.
 4. The apparatus of claim 1 whereinsaid tubing has an exterior circumferential recess and said balloon isdisposed in said recess.
 5. The apparatus of claim 1 furtherincluding:a. a helically wound spring attached to said distal end ofsaid tubing, said spring terminating in a smooth rounded tip; and b. aspring stiffening member attached to said core member adapted to fitwithin said spring upon moving said core toward said distal end of saidspring.
 6. The apparatus of claim 5 wherein said spring and said springstiffening member are mutually tapered toward said distal end.